21020617 has 2 divisors, whose sum is σ = 21020618. Its totient is φ = 21020616.

The previous prime is 21020611. The next prime is 21020627. The reversal of 21020617 is 71602012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15872256 + 5148361 = 3984^2 + 2269^2 .

It is a cyclic number.

It is not a de Polignac number, because 21020617 - 2¹⁵ = 20987849 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21020594 and 21020603.

It is not a weakly prime, because it can be changed into another prime (21020611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510308 + 10510309.

It is an arithmetic number, because the mean of its divisors is an integer number (10510309).

Almost surely, 2^21020617 is an apocalyptic number.

It is an amenable number.

21020617 is a deficient number, since it is larger than the sum of its proper divisors (1).

21020617 is an equidigital number, since it uses as much as digits as its factorization.

21020617 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 168, while the sum is 19.

The square root of 21020617 is about 4584.8246422301. The cubic root of 21020617 is about 275.9826749960.

Adding to 21020617 its reverse (71602012), we get a palindrome (92622629).

The spelling of 21020617 in words is "twenty-one million, twenty thousand, six hundred seventeen".